Title says it. Rather not try to use hose clamps. I want to add the 2nd bottle cage to the underside of the down tube. Don't know about thread inserts on CF. I guess I could pop-rivet it directly, but that seems sketchy.

Have emergency tool kit bag hanging out behind the back of the seat, lights also and bars are full.

Don in Austin

I don't want to be the one that recommends drilling your CF frame, but since the builders do it, it must be OK within reason. Riv-nuts are the way to go. Make a template or gauge and check the hole position 3 times to be 100%+ sure before drilling because you don't want to do this twice.

After drilling, seal the sides of the hole with nail polish. I also put a dab of body filler around both the inside and outside riv-nut flanges to accommodate the tube curvature and make a bed for the nut.

If you have an open BB, remove it so drill chips don't make a problem. If it's a cartridge, you can leave it an and shake out any chips next time you remove it for service.

It has riv-nuts now for the existing cage. What do I do about the tool without spending a fortune? Not too worried about precise hole location as the cage holes are slots.

Thanks....Don

I was less concerned with the hole separation, than getting both truly on the centerline.

If you already own a pop riveter, it might also accept riv-nuts. Otherwise, ask around at the various shops to see who has one, and would be willing to install the inserts if you prepare the site. It shouldn't be expensive if you already have a relationship, and they'd probably say no if you don't.

Don: Not to say it couldn't be done successfully, but I'd personally be real nervous about drilling into a CF frame. This post has a slew of alternative water bottle mounting schemes:
https://recklesscognition.wordpress.c...ws-and-bosses/

To add yet another option, TwoFish makes a bottle mount:

https://www.treefortbikes.com/product...e-Adapter.html



I just finished a 72-mile ride on road and gravel, with one of these strapped to the underside of my CF mountain bike's downtube. It was carrying a 24-ounce bottle and seems to be doing the trick.

When started reading the thread I thought in this product aswel, nice stuff.

The downtube of this CF bike is large and sort of rectangular.
Don in Austin

I used this method to install a pair on a friend's aluminum bent. https://www.parktool.com/blog/repair-...ottle-fittings

Here's a REALLY exhaustive list of alternatives:https://www.nordicgroup.us/cageboss/

Well, mine is large and sort of mostly-round. The part that goes against the frame is pliable rubber, this is the same company that makes the popular LockBlock and CycleBlock flashlight holders. It should have no problem conforming to the tube if you want to try one.

Riv nuts can be expanded with their own bolt, pulling the threaded bit against the external flange.

Tool is not compulsory .. I haven't tried the Seat post QR as a tool to pull the expansion in place,

But it has some logic to it ..
maybe with a wrap of Fiberglass and epoxy as a tape around the riv nut

if they use 7000 series aluminum in those..